diff --git a/filter/edit.cgi b/filter/edit.cgi
index f59952005..ff9e7209b 100755
--- a/filter/edit.cgi
+++ b/filter/edit.cgi
@@ -87,6 +87,7 @@ else {
 		$regexp = 1;
 		}
 	}
+$condvalue = &mailbox::decode_mimewords($condvalue);
 print &ui_table_row(
 	&ui_oneradio("cmode", 4, $text{'edit_cmode4'}, $cmode == 4),
 	&text('edit_cheader2',
diff --git a/filter/filter-lib.pl b/filter/filter-lib.pl
index 57bbb3d52..2199e1a6f 100755
--- a/filter/filter-lib.pl
+++ b/filter/filter-lib.pl
@@ -533,6 +533,7 @@ return wantarray ? ( $cond, $lastalways ) : $cond;
 
 # prettify_regexp(string)
 # If a string contains only \ quoted special characters, remove the \s
+# Also, undo any mimewords encoding.
 sub prettify_regexp
 {
 my ($str) = @_;
@@ -541,7 +542,7 @@ $re =~ s/\\./x/g;
 if ($re =~ /^[a-zA-Z0-9_ ]*$/) {
 	$str =~ s/\\(.)/$1/g;
 	}
-return $str;
+return &mailbox::decode_mimewords($str);
 }
 
 # describe_action(&filter, &folder, [homedir])
diff --git a/filter/save.cgi b/filter/save.cgi
index 8144d9b65..7c0175029 100755
--- a/filter/save.cgi
+++ b/filter/save.cgi
@@ -83,7 +83,10 @@ else {
 		$filter->{'condheader'} = $in{'condmenu'} || $in{'condheader'};
 		$filter->{'condheader'} =~ /^[a-zA-Z0-9\-]+$/ ||
 			&error($text{'save_econdheader'});
-		$in{'condvalue'} = &mailbox::encode_mimeword($in{'condvalue'});
+		if ($in{'condvalue'} !~ /^[\000-\177]*$/) {
+			$in{'condvalue'} = &mailbox::encode_mimewords(
+				$in{'condvalue'}, 'Charset' => &get_charset());
+			}
 		if (!$in{'condregexp'} &&
 		    $in{'condvalue'} =~ /[\^\$\.\*\+\?\|\(\)\[\]\{\}\\]/) {
 			# If the user didn't ask for a regexp but there are